Abstract: An apparatus and method is described that is used to design a minimal spares network for a given communications network. Three data files are used as input which describe the communications network. The information comprising such data files include the number and configuration of the nodes and spans, the current demand in terms of the required capacity between the source and destination nodes, current spare capacity (if any), and optionally current paths used to carry the demand traffic (including the presence or absence of glass-throughs). A three pass method is used to design an efficient and economical spares network from the given input data. A simulated cut is performed on each span in the communications network. From each simulated span cut, the affected demand traffic is identified and rerouted via spare capacity that is `purchased` on an incremental cost basis. Pre-purchased spares are used before new spares are purchased.

Abstract: The invention provides means for detecting errors in the transmission of protocol data words between the handset station and base station of a cordless telephone set. Assuming the protocol data words are eight bits in length, a sixteen bit security code word is provided which consists of a high security byte and a low security byte. At the transmitting station (either the hand set or base), the protocol data byte is exclusive-ored with both the high security byte and the low security byte. The two resulting bytes are appended to the original protocol data byte to form a twenty-four bit error detection code. This error detection code is transmitted to the receiving station. The receiving station takes the unaltered protocol byte portion of the three byte word and exclusive-ors it with both of the other bytes of the received word. If there were no transmission errors, the sixteen bit security code should be generated by the exclusive-oring step.